Sudoku Tutorial #11-A / X Wing Examples & Tips

[@remyrat8961]

I watched the examples again and again. And made detailed notes, so I can refer to it later if needed. First I had some dificulties in finding sashimi X-wings, but I found a way to make it easier. Only when I see a conjugate pair, I’m on the lookout for them. I found out that if you scan the grid with the conjugate pair as a starting point. And it works! Yesterday I found a sashimi X-wing in a real puzzle. That sashimi was staring at me!

[@LordTreyHowdy]

Finally, sashimi makes sense! Thank you for the clear explanation

[@SudokuSwami]

Glad to hear it. Good luck!

[@maximusgladus]

Sudoku Swamis tutorials are by far the best on KZbin! I would suggest that you make a slight pause after announcing what digit you are filtering for so that viewers have time to pause and practice the solution before you give the answer. Thank you.

[@SudokuSwami]

When making the Videos, I try to save as much time as possible. Otherwise, they can get very long. I understand what you are saying, but my advice is to please pause the Video yourself, by clicking on the Pause Button. Thank you.

[@SudokuSwami]

If you enjoyed this Video, please don't forget to click the SUBSCRIBE button, and the Thumbs Up Icon. It will really help me out. Thank you!

[@robertan.2491]

Thank you for another super clear tutorial, I see now where I have been making mistakes

[@SudokuSwami]

Glad to hear it. Good luck!

[@rezamiau]

In 6:52 you could also choose C2 and C8. You're a Great Tutor Sudoku Swami. Thank you.

[@SudokuSwami]

You are absolutely correct about C2 & C8. Good observation. And I really appreciate your interest in my Tutorials, and your fine compliment. Good luck!

[@raycicin1794]

The fog is slowly lifting, Thank you for all these lessons.

[@lesleywillis6177]

At 26:48 you eliminated R8 c8 as an AIC or skyscraper. I had paused the puzzle and spotted that elimination as the sashimi x wing that I thought I was looking for.

[@SudokuSwami]

A Skyscraper can always be seen as TWO separate Sashimi X-Wings, each with only one Fin. But it is always more efficient to view it as a Skyscraper, because you get the same eliminations with only one operation, instead of two.

[@daleerwin7554]

I'm feeling pretty good about just making an elimination using a finned x-wing. I think it's the first one I've ever found. Lots of x-wings, but my first one finned. Still have never had a sashimi x-wing.

[@CasaErwin]

So far, I have found two Finned X-Wings. In both cases, even without the fin, there would have been nothing to eliminate.

[@tomaszwasilewski1650]

It seems to me that in 14:52 no matter which fin or base candidate was chosen, all 6's from cover set in row 7 can be eliminated.

[@SudokuSwami]

The Hand-Drawn diagrams (such as this one) are NOT REAL PUZZLES. They are meant for demonstration purposes only. Please try to focus on the point I am trying to make instead of over-analyzing these configurations.

[@ItsNiklas]

Hi, love your videos. Could you tell me the name of the tool used to draw the arrows visualizing the links? Thanks :)

[@SudokuSwami]

Yes, it's called "The Arrow Tool." Ha-ha. Just kidding! Thank you for your interest and support. I do not like to discuss software here on my Channel. Please write to me at [e-mail], and I will be happy to answer your question(s). :-))

[@eileen269]

Hi, at 25:04 could R4 C7 also be eliminated? (Is this a skyscraper as well?) Thanks!

[@SudokuSwami]

You must have written the time incorrectly. Your question doesn't make any sense. Please check the time, and please try to be more specific (regarding which Candidates, as well as Cells, that you are talking about). Thank you.

[@eileen269]

Sorry, try 24:57 ... Could R6 C9 and R4 C2 be the endpoints of an upside down skyscraper ?

[@SudokuSwami]

Ha ha! Yes! I have to be honest, at first I thought you were crazy. But yes, it is indeed an upside-down Skyscraper, which would eliminate the 5's in both R4C7 and R6C3. Because I was demonstrating the Sashimi X-Wing, I was not paying attention to any available Skyscrapers. But as I am sure I have pointed out in one or two of my Videos, (but at this moment I cannot tell you precisely where), that any Sashimi X-Wing with only 1 Fin, can always be perceived as a Skyscraper. The other Sashimi X-Wing occurring at the same time, in that diagram, would be with the Sashimi Cell being R4C9 and the Fin being R6C9, which would produce the other elimination in R4C7, as you pointed out. But the Skyscraper gets both eliminations at once. Good observation. :-)) When a Sashimi X-Wing has 2 Fins, then it will not work as a Skyscraper.

[@eileen269]

@@SudokuSwami Thanks so much for confirming the skyscraper. I'm happy to know that I'm grasping the concepts and am not crazy after all! You are an excellent instructor!

[@cloptete1979]

What software do you use please? I love your videos

[@SudokuSwami]

Hello Paul, for discussions of software, please write to me at [e-mail] Thank you.

[@nelisvandeursen5625]

Thans you

[@nataliemowrey8783]

I'm confused about locating the fin. I understand that it is located in the same block as the missing candidate, but should I look vertically or horizontally? E.g., @27.07 Candidate 1, why is the fin in C8R4, not C9R5and R6?

[@SudokuSwami]

In an X-Wing, the Fins can only be in one of the Base Sets. In the example you cite, the Base Sets are Row 4 and Row 7. Eliminations are made in the Cover Sets, which in this case, are Column 1 and Column 9. Since the Fin is in Block 6, Eliminations can only be made in that Block in the Cover Set of Column 9. The logic is: The Fin is either True or False. 1.) If the Fin is False, then you would have a Regular X-Wing, in which case the 1's in R5C9 and R6C9 would be False. 2.) If the Fin is True, then again, the 1's in R5C9 and R6C9 would also be False. Since those two Candidates would be False EITHER WAY, then you know it is a Verity, and that they can be confidently eliminated as False.

[@a_son_of_light]

Sashimi: A Japanese dish consisting of very thin bite-size slices of fresh raw fish, traditionally served with soy sauce and wasabi.

[@artistaccelerator]

Does a sashimi HAVE to have two fins?

[@SudokuSwami]

No. It can have one or two Fins. BUT...if it has only one Fin, then you can envision it as two separate Sashimi X-Wings. But as I think I mentioned, if it has only ONE Fin, then it is quicker and more efficient to envision it as a Skyscraper: Tutorial #16 kzbin.info/www/bejne/a2q9kqaVZ997hck

[@satorikomeiji3043]

It's getting hard from now, the hidden tripples and finned/sashimi x wings is not easy to find :(

[@SudokuSwami]

The best way to find Hidden Pairs and Hidden Triples, is to look for Quads and Quints.

[@satorikomeiji3043]

So you mean finding naked subsets with large size, like 4 or 5 is equal to find hidden paris and triples? After you find these subsets, you can eliminate these candidates in the rest of the house? If so, finding naked subset is ok as long as you can find subsets with size 2 to 5 or 6?

[@SudokuSwami]

Many times you will see that a Hidden Pair or a Hidden Triple is accompanied by a Naked Triple, Quad or Quint, in the same House. It is just a different way of seeing the same thing. For instance, if in a Row (or any House), there are two Cells filled in, so that there are seven unfilled Cells, it will quite often be the case that you will see a Naked Quad and a Hidden Triple, or a Naked Quint and a Hidden Pair. By making the resulting eliminations from the larger Naked Subset, the smaller Hidden Subset will be revealed. It is good to be able to see it either way. :-))

[@satorikomeiji3043]

Yeah, I get that. I come out a good way to find hidden pairs or even triple. To find candidates that occurs least in a house, if they form a "hidden subset", that is hidden pairs or tripples.

[@rethink150]

At 21:47 puzzle ,is there another xwing with fins in columns 1 & 7 #9 at rows 3 & 7 with fins on colum 7 ,rows 1 & 2 ?

[@SudokuSwami]

Yes. But this is an unproductive configuration, because there are no Candidate Eliminations available from it. The only Cells where you could eliminate a 9 from your Finned X-Wing would be R3, C8 & C9, and both of those Cells are already solved.

[@rethink150]

@@SudokuSwami Thanks ,I was learning to identify them

[@charlesmangum3108]

Review, review, review.

[@SudokuSwami]

Learn, learn, learn. And you won't have to review, review, review. Ha-ha.

[@charlesmangum3108]

reviewing is part of learning

[@SudokuSwami]

It was a joke....

[@charlesmangum3108]

not to worry